1. Field
The following description relates to an optical device, and more particularly, to a light screening device and a manufacturing method thereof
2. Description of the Related Art
A light screening apparatus is a common feature of apparatuses which require the prevention of light transmission. An optical shutter, which is a kind of light screening apparatus, is an optical device which allows transmission of light only during a specific time interval. For example, an optical shutter embedded in a camera module blocks or allows the passage of light passing through a camera lens. By changing a driving speed of the optical shutter and/or varying a range of screening the camera lens (i.e. an opening size of the optical shutter), the optical shutter may be used to adjust a time at which light to be transmitted to an image sensor is received and/or the received amount of light. The light screening apparatus, e.g. an optical shutter, is also used for any other optical devices requiring a temporary, selective or permanent light-screening function, as well as for camera modules.
Following on from mechanical optical shutters, electronic optical shutters have been developed. An electronic optical shutter controls a time interval during which an image sensor receives light by turning on/off the image sensor. Since the electronic optical shutter operates by use of a circuit, it has been widely used for digital cameras having limitations in camera module size. However, using such an electronic optical shutter, and due to the increased number of pixels of a camera module, moving object distortion may easily occur.
Recently, with the ever increasing number of pixels of a digital camera embedded in a mobile device, interest for a mechanical optical shutter is again increasing. Due to requirements for small-sized, thin electronic devices, the mechanical optical shutter also needs to be small-sized and thin. Also, light passing through a camera lens has to be completely blocked when the mechanical optical shutter is closed, and when the mechanical optical shutter is opened, light passing through the camera lens has to be uninterrupted. In addition, in order to support a high-definition, high-performance camera module, the mechanical optical shutter has to provide a very quick response (shuttering) speed.